A Phase 3 interventional study of Proton Therapy in Breast Cancer, sponsored by Proton Collaborative Group. Recruiting at 9 sites in United States. Open to female participants aged 19 Years and older. Per ClinicalTrials.gov, last updated 2026-09-29.
Sponsored by Proton Collaborative Group · Phase 3, Interventional, and Treatment
The purpose of this research study is to learn more about the effects of using proton radiation therapy delivered over a shorter course of treatment (3 weeks) compared with a longer, standard course of treatment (5 weeks) for women with breast cancer who require radiotherapy to the breast/chest wall and regional lymph nodes.
This study is being done to see if comprehensive regional nodal radiation therapy to the breast or chest wall and regional lymph node area using proton therapy delivered with a hypofractionated approach (less treatment days) will result in rates of treatment related skin and soft tissue side effects that are non-inferior compared to conventionally fractionated proton radiotherapy regimens.
Exclusion Criteria:
50-50.4 Gy (RBE) in 25-28 daily fractions of 1.8-2.0 Gy (RBE) plus a Tumor Bed Boost (for intact breast) of 10 Gy (RBE) in 4-5 daily fractions of 2-2.5 Gy (RBE) \*\*Additional boost of 10-20 Gy (RBE) in 2-2.5 Gy (RBE) fractions to clinically involved lymph nodes or chest wall/scar allowed at the treating physician's discretion\*\*
Radiation: Proton Therapy
40.05 Gy (RBE) in 15 daily fractions of 2.67 Gy (RBE) plus a Tumor Bed Boost (for intact breast) of 10 Gy (RBE) in 4-5 daily fractions of 2-2.5 Gy (RBE) \*\*Additional boost of 10-20 Gy (RBE) in 2-2.5 Gy (RBE) fractions to clinically involved lymph nodes or chest wall/scar allowed at the treating physician's discretion\*\*
Radiation: Proton Therapy
Pencil Beam Scanning (PBS)
To determine if the rate of grade ≥3 treatment-related skin and soft tissue toxicities with comprehensive nodal irradiation for breast cancer using hypofractionated PBS proton therapy is non-inferior to conventionally-fractionated proton radiotherapy
This study will investigate if adjuvant comprehensive regional nodal radiotherapy to the breast or chest wall and regional lymph nodes including the axilla (levels I-III), supraclavicular (SCV), and internal mammary (IMN) lymph nodes using pencil beam scanning proton therapy delivered with a hypofractionated regimen results in rates of acute and late grade 3 or worse treatment-related skin and soft tissue toxicities that are non-inferior compared with rates in pencil beam scanning proton therapy using conventionally fractionated regimens.
Time frame: 2 years after radiation therapy
To determine the rate of any grade ≥3 treatment-related adverse events
Time frame: 2, 5, and 10 years after radiation therapy
To determine local recurrence rates
Time frame: 2, 5, and 10 years after radiation therapy
To determine regional recurrence rates
Time frame: 2, 5, and 10 years after radiation therapy
To determine distant recurrence rates
Time frame: 2, 5, and 10 years after radiation therapy
To determine breast cancer-specific survival
Time frame: 2, 5, and 10 years after radiation therapy
To determine overall survival
Time frame: 2, 5, and 10 years after radiation therapy
To assess patient-reported quality of life
FACT-B questionnaire
Time frame: 2, 5, and 10 years after radiation therapy
To assess patient-reported quality of life
BREAST-Q questionnaire
Time frame: 2, 5, and 10 years after radiation therapy
To assess physician-reported cosmetic outcomes
Physician reported cosmesis form
Time frame: 2, 5, and 10 years after radiation therapy
To correlate dosimetric parameters with acute and late adverse events for the development of model dose constraints for comprehensive nodal irradiation for breast cancer using a moderately hypofractionated regimen with PBS-PT
Time frame: 2, 5, and 10 years after radiation therapy
Plan to share: No
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Proton Collaborative Group